Most of the time, a single knife is commonly used for peeling potatoes.
U.S. Pat. No. 4,430,931 dated Feb. 14, 1984 describes a peeling device consisting of pairs of knives for generally cylindrical vegetables held in fixed position and resulting in a defined geometric shape but which does not follow the initial contour of the potato.
U.S. Pat. No. 1,988,098 reveals peeling knives carried by spring restained arms in position for peeling leguminous tubers but the vegetable is not free to move.
U.S. Pat. No. 2,699,806 describes knives so arranged to slit the skin of nuts, as an industrial machine, but too complex for home utilization.
There are some peeling devices provided with means to control deepness of the peel removed. Even with special kind of knife it takes two hands, dexterity and time to get a clean economical result. Some care is needed to collect the wastes; if potatoes have not been previously washed, peeling is a messy operation.